Vapor generator and structural unit therefor

ABSTRACT

The structural units are prefabricated to define the heating surfaces of the vapor generator. Each unit is formed of pipe panels disposed in parallel in a horizontal plane as well as wall parts which define a part of the sidewalls of the vapor generator. Some units have pipe ends which extend through the wall parts in gastight relation in order to connect to a header or manifold.

United States Patent Inventor llarendra Nath Sharan Seuzach, Zurich, Switzerland Appl. No. 29,423

Filed Apr. 17, 1970 Patented Sept. 28, 1971 Assignee Sulzer Brothers, Ltd.

Wlnterthur, Switzerland Priority Apr. 17, 1969 Switzerland VAPOR GENERATOR AND STRUCTURAL UNIT THEREFOR 13 Claims, 4 Drawing Figs.

11.8. CI 122/6 A, 122/494 Int. Cl F22b 37/24 Field of Search .1 122/6, 6 A,

[56] References Cited UNITED STATES PATENTS 3,081,748 3/1963 Koch 122/406 3,030,937 4/1962 Witzke 122/6 2,952,975 9/1960 Braddy 122/478 X 2,803,227 8/1957 Marshall 122/478 Primary Examiner1(enneth W. Sprague Attorney-Kenon & Kenyon Reilly Carr & Chapin ABSTRACT: The structural units are prefabricated to define the heating surfaces of the vapor generator. Each unit is formed of pipe panels disposed in parallel in a horizontal plane as well as wall parts which define a part of the sidewalls of the vapor generator. Some units have pipe ends which extend through the wall parts in gastight relation in order to connect to a header or manifold.

mnm zm SHEET 0F 4 In ventor M R/mam Nam S/mAw v VAPOR GENERATOR AND STRUCTURAL UNIT THEREFOR This invention relates to a vapor generator. More particularly, this invention relates to structural units for the construc- 'tion of a vapor generator.

Vapor generators have been known wherein a wall pipe system formed from vertical interwelded pipes defines a space having a cross section with two sides parallel to each other. The wall pipe system is further constructed so that a flue gas can flow in a vertical direction through the pipe enclosed space and so that at least one combustion chamber can extend into the lower end of the space with heating surfaces in the form of pipe nests above the combustion chamber. Generally, the pipe nests which form the heating surfaces and the walls defining the space for the flow of flue gas have been manufactured individually in a workshop and then assembled at a building site. However, this has led to relatively large fabrication and erection costs as well as relatively long construction periods. I

Accordingly, it is an object of the invention to reduce the costs of producing vapor generators.

It is another object of the invention to provide prefabricated vapor generator units which can be easily installed at a building site.

It is another object of the invention to reduce the costs required for erecting a vapor generator.

Briefly, the invention provides a vapor generator which is constructed of a number of prefabricated units. Each prefabricated unit includes a pipe nest in which the pipe members are coiled in a serpentine or meander fashion to extend substantially horizontally in parallel relation. The two opposite ends of each unit are also formed so as to define a section of a wall of the vapor generator while the individual ends of the pipe members of the pipe nest extend through and are welded in gastight manner to the wall part.

The prefabricated units are stacked and interconnected in the field so as to form a wall pipe system of vertical interwelded pipes with two end walls of substantially gastight construction. A pair of sidewalls of interconnected pipes are then interconnected to the stacked units so as to define a flue space for the flow of a flue gas. A combustion chamber is then mounted in the lower end of the generator to provide for a flow of flue gas.

One advantage of the invention is that different parts of a vapor generator namely the pipe nests and the pipe walls can be prefabricated in a workshop into units which can be assembled at a building site in a rapid and economical manner. Further, prefabrication of a plurality of structural units can be carried out simultaneously. Both of these features in combination reduce the building period in addition to lowering costs. A further reduction of costs is obtained by virtue of the fact that an increased proportion of the welding work is performed in the workshop where, since the welding positions are more readily acceptable, such welding operations can be performed and inspected more accurately than on the installation site. Very substantial advantages are obtained if the invention is applied to vapor generators in which the cross section of the space traversed by the flue gases is at least twice as large in the direction of the pipe members as the distance between parallel walls.

The invention also provides a method for the production of a vapor generator, characterized in that the structural units are prefabricated in a workshop, are then transported to a building site, assembled and welded to each other. Although, in its entirety, a vapor generator according to the invention has more welding seams than vapor generators manufactured in a conventional manner, the vapor generator according to the invention is less costly because the welding operations on the building site are confined to a smaller number of welding seams than is the case in the conventional construction. Accordingly, the proportion of welding work performed in the workshopis therefore greater than the increase in the number of welding seams.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a simplified perspective view of a vapor generator according to the invention;

FIG. 2 illustrates a perspective view to a large scale than FIG. 1 of a structural unit of the vapor generator of FIG. 1;

FIG. 3 illustrates a vertical section view of part of the structural unit of FIG. 2; and FIG. 4 is a side elevation view of an end of the structural unit of FIG. 2.

Referring to FIG. 1, a support structure of four U-shaped girders 1, each of which is of l-cross section with the ends of each embedded in the ground, supports the vapor generator 2 in a suspended manner, as is known, and at the same time represent the structure for the building surrounding the vapor generator. The vapor generator 2 substantially comprises a front wall 3, a rear wall 4 disposed in parallel to the front wall 3, and two sidewalls 5 (of which only one is shown) which join the front wall 3 and the rear wall 4. The four walls 3-S are formed from vertical pipes 6 which are interwelded in gastight manner and extend at the upper ends into headers l3, l4, 15 associated with one wall each. In addition, the lower ends of the pipes 6 are connected to corresponding manifolds disposed below the floor (not shown). All the wall pipes 6 are connected as preheater heating surfaces and define a'space for the passage of a flue gas. In addition, a number of turbulence muffle burners 8, e.g. five, are disposed in the lower part of each of the front wall 3 and rear wall to extend into the space defined by the four walls 35.

An air preheater 20, supplied from below with combustion air which is preheated by means of flue gases supplied via a pipeline 30, is provided on the right-hand side, as viewed, adjacent to the vapor generator. The preheated fresh air is conv eyed via a duct 21, a fresh air blower 22 and two distribution ducts 23 and 24 to the muffle burners 8.

The upper relative cold end of the vapor generator 2 is formed into a sheet metal hood 7, which is connected to the duct 30 in order to direct the flue gases from the vapor generator 2 into the duct 30.

According to one embodiment, the vapor generator 2 is constructed from four structural units 50, 53, 56 and 59. The lowermost structural unit 50 comprises a pipe nest 10 constructed in this case of a plurality of pipe panels which are disposed next to each other in the flue gas flow, and of a wall part forming part of the two sidewalls 5. The pipe ends of the pipe nest 10 extend through the wall part (not shown) and are connected to a manifold 51 and a header 52, respectively, which are disposed outside the space through which the flue gases flow and in parallel to the sidewall 5. The pipe nest 10 of the structural unit 50 forms an evaporator heating surface.

The next higher structural unit 53, whose pipe nest 11 forms a superheater surface, is of the same basic construction as the lowermost unit 50. The only difference in this case being that the manifold 48 and the header 49 are disposed on two opposite sides and accordingly two wall parts, each forming part of the two sidewalls, are incorporated in the structural unit 53. The same applies to the structural units 56 and 59 whose pipe nests l2 and 19 form an intermediate superheater surface or an economizer surface.

Referring to FIG. 2, the structural unit 53 contains the superheater pipe nest 11, comprising six pipe panels disposed in parallel next to each other. Each pipe panel is constructed from four pipes curved into a serpentine or meander pattern and all of which extend along the panel plane. One set of pipe ends 11' (FIG. 3) of the pipe nest 11 extend through the lefthand wall part 35 which forms a part of one sidewall 5 (FIG. I). Referring to FIG. 4, the pipes 6 of the wall parts 35 are offset in pairs and in opposite orientations in the zone in which they extend through the pipe wall and webs 60, to which the pipe ends 11' of the pipe nest are welded, are welded between the pipes 6. The pipe nest 11 is thus mounted by means of the webs 60 on the wall part 35 and the correspondingly constructed wall part of the oppositely disposed sidewall 5.

In order to suspend the pipe panels from the support structure, tubular supporting members 45 extend between the pipe panels and are distributed over the length of the pipe nest. The tubular supporting members 45 extend upwardly and downwardly beyond the height of the pipe panels and are mounted by welding on the pipe panels.

Bending of the pipes to form the pipe panels, joining of the pipe panels to the respective manifolds and headers, and welding to the wall parts and to the tubular supporting members is performed in the workshop so that each of the structural units form one prefabricated part of the vapor generator 2.

Referring to FIG. 2, in order to facilitate transportation from the workshop to the building site, each structural unit is provided with a transportation frame comprising four longitudinal girders 37, 38, 39 and 40 (FIG. 3), frame members 41 for joining the girders in pairs as well as a plurality of transverse members 42 e.g. l6 forjoining the longitudinal girders. The two sidewall parts 35 are mounted on the external transverse member 42 by means of U-bolts 43, as indicated in FIGS. 3 and 4. The remaining transverse members 42 are disposed to lie adjacent the extensions of the tubular supporting member 45 joined to the pipe panels. The ends of these tubular supporting members 45 are also secured by means of U- bolts on the transverse members 42. The dimensions of the structural unit are so selected that, when assembled with the transportation frame, the unit can be transported on railway trucks.

After transportation of the structural units to the building site, the units are hoisted on the supporting structure already erected and are mounted thereon or under a structural unit already installed namely by welding of the two wall parts 35 and the tubular supporting member 45. The transportation structure is then removed and may be reused in the workshop. Subsequently, the front wall 3 and the rear wall 4, which, in accordance with the size of the vapor generator are constructed in one or more parts which may also be prefabricated in the workshop, are welded at the building site to the assembled structural units. The walls 3, 4 and 5 are then externally covered with sheet metal panels which are also joined in gastight manner. The conventional buckstays (not shown) are then mounted. Any buckstays which may be required for the sidewalls 5 may be mounted on the sidewall parts during prefabrication in the workshop. Finally, the burners 8 are mounted.

In the vapor generator described hereinabove, the length of the structural unit as measured in the direction of the pipe members of the pipe nests, is equal to the width of the vapor generator and the width of the structural units as measured at right angles to the parallel walls 3 and 4, is equal to the depth of the vapor generator. According to an embodiment of the invention, the length of each structural unit may be equal to half the width of the vapor generator. Furthermore, it is also possi ble for the width of the structural units to be so selected that twice the depth or a multiple of the depth is obtained by the adjacent placing of several structural units.

What is claimed is:

l. A structural unit for a vapor generator comprising a pipe nest having a plurality of pipe panels extending in a substantially vertical plane in parallel relation, and at least one wall part including a plurality of vertically disposed interconnected pipes; each of said panels having at least one pipe wound in a meander fashion with one end thereof extending through said wall part and being secured thereto in gastight relation.

2. A structural unit as set forth in claim 1 wherein the length of the unit is at least twice the width of the unit.

3. A structural unit as set forth in claim 1 which further includes a manifold connected in common to said ends extending through said wall part.

4. A structural unit as set forth in claim 1 wherein said panels are adjacent each other.

5.Avapor generator comprisinfi a wall pipe system of vertica y disposed interconnected pipes defining a space of a cross section with two parallel sides for the flow of a flue gas;

at least one combustion chamber at the lower end of the space; and

a plurality of structural units forming heating surfaces within the space of said wall pipe system, each unit including a pipe nest having a plurality of vertically upstanding pipe panels extending horizontally parallel to said sides and at least one wall pan including a plurality of vertically disposed pipes forming a part of said wall pipe system to define a further side of the space, each of said panels having at least one end ofa pipe thereofextending through said wall part in gastight relation.

6. A vapor generator as set forth in claim 5 wherein each structural unit is of a length approximately equal to the width of the vapor generator.

7. A vapor generator as set forth in claim 5 wherein each structural unit is of a length equal to approximately one-half the width of the vapor generator.

8. A vapor generator as set forth in claim 5 wherein each structural unit is ofa width perpendicular to said parallel sides approximately equal to the depth of the vapor generator.

9. A vapor generator as set forth in claim 5 wherein said combustion chamber is a turbulence combustion chamber for complete combustion therein.

10. A method of constructing a vapor generator comprising the steps of prefabricating a plurality of structural units defining heating surfaces for the vapor generator and at least a part of the sidewalls of the vapor generator,

transporting the structural units to a building site,

erecting the structural units on each other in stacked relation; and

welding the structural units together.

11. A method as set forth in claim 10 which further comprises the steps of prefabricating at least a pair of pipe walls, transporting the pipe walls to the building site and welding the pipe walls to the stacked structural units in parallel relation to the structural units to define a space between the pipe walls and sidewalls for the flow of a flue gas past the heating surfaces.

12. A vapor gencrator as set forth in claim 5 wherein at least some of said structural units each have a pair of said wall parts on opposite ends and said panels have at least one end of a pipe thereof extending through each said respective wall part in gastight relation.

13. A vapor generator as set forth in claim 5 wherein said pipes of two parallel sides of said space for the flow of a flue gas are of greater height than the height of one of said structural units. 

1. A structural unit for a vapor generator comprising a pipe nest having a plurality of pipe panels extending in a substantially vertical plane in parallel relation, and at least one wall part including a plurality of vertically disposed interconnected pipes; each of said panels having at least one pipe wound in a meander fashion with one end thereof extending through said wall part and being secured thereto in gastight relation.
 2. A structural unit as set forth in claim 1 wherein the length of the unit is at least twice the width of the unit.
 3. A structural unit as set forth in claim 1 which further includes a manifold connected in common to said ends extending through said wall part.
 4. A structural unit as set forth in claim 1 wherein said panels are adjacent each other.
 5. A vapor generator comprising a wall pipe system of vertically disposed interconnected pipes defining a space of a cross section with two parallel sides for the flow of a flue gas; at least one combustion chamber at the lower end of the space; and a plurality of structural units forming heating surfaces within the space of said wall pipe system, each unit including a pipe nest having a plurality of vertically upstanding pipe panels extending horizontally parallel to said sides and at least one wall part including a plurality of vertically disposed pipes forming a part of said wall pipe system to define a further side of the space, each of said panels having at least one end of a pipe thereof extending through said wall part in gastight relation.
 6. A vapor generator as set forth in claim 5 wherein each structural unit is of a length approximately equal to the width of the vapor generator.
 7. A vapor generator as set forth in claim 5 wherein each structural unit is of a length equal to approximately one-half the width of the vapor generator.
 8. A vapor generator as set forth in claim 5 wherein each structural unit is of a width perpendicular to said parallel sides approximately equal to the depth of the vapor generator.
 9. A vapor generator as set forth in claim 5 wherein said combustion chamber is a turbulence combustion chamber for complete combustion therein.
 10. A method of constructing a vapor generator comprising the steps of prefabricating a plurality of structural units defining heating surfaces for the vapor generator and at least a part of the sidewalls of the vapor generator, transporting the structural units to a building site, erecting the structural units on each other in stacked relation; and welding the structural units together.
 11. A method as set forth in claim 10 which further comprises the steps of prefabricating at least a pair of pipe walls, transporting the pipe walls to the building site and welding the pipe walls to the stacked structural units in parallel relation to the structural units to define a space between the pipe walls and sidewalls for the flow of a flue gas past the heating surfaces.
 12. A vapor generator as set forth in claim 5 wherein at least some of said structural units each have a pair of said wall parts on opposite ends and said panels have at least one end of a pipe thereof extending through each said respective wall part in gastight relation.
 13. A vapor generator as set forth in claim 5 wherein said pipes of two parallel sides of said space for the flow of a flue gas are of greater height than the height of one of said structural units. 